1. Field of the Invention
The present invention relates to an ink jet print head which includes a fluid passage forming substrate having pressure generating chambers formed by anisotropically etching a silicon monocrystalline substrate.
2. Related Art Discussion
A conventional ink jet print head is shown in FIG. 9. As shown, the print head has a layered structure which is made up of a fluid passage forming substrate 51, a covering member 55, and an elastic plate 57. The fluid passage forming substrate 51 includes a pressure generating chamber 50 that receives an external pressure. The covering member 55 has a discharge orifice 54 communicating with the pressure generating chamber 50 and an ink supplying port 53 communicatively connecting a reservoir 52 to the pressure generating chamber 50. The elastic plate 57 has a pressure generating means 56 and covers one of the major sides of the fluid passage forming substrate 51. The pressure generating chamber 50 is expanded and contracted by the pressure generating means 56 of the elastic plate 57. When expanded, the pressure generating chamber sucks ink from the reservoir 52 through the ink supplying port 53. When contracted, the pressure generating chamber causes the sucked ink to eject outside in the form of ink droplets through the discharge orifice 54.
In forming the fluid passage forming substrate 51 having the pressure generating chambers 50 formed therein, an etching pattern corresponding to an array of pressure generating chambers is formed on a silicon monocrystalline substrate having a face (110). Then, the structure is etched in an alkaline water solution containing potassium hydroxide by an anisotropical etching process. In the process of anisotropically etching the silicon monocrystalline substrate, recesses and openings having (111) faces that are vertical to the (110) face are linearly formed. The recesses and the openings are considerably high in their aspect ratio. The result is the formation of pressure generating chambers arrayed at extremely high density.
In the silicon monocrystalline substrate having a (110) face, (111) faces appear, which are each slanted at about 35xc2x0 with respect to the surface of the silicon monocrystalline substrate, and extended from the intersection of linear patterns along the (111) faces vertical to the (110) faces. These faces (111) form the walls 58 and 58xe2x80x2 of each pressure generating chamber 50.
With the formation of the slanted walls, acutely angled spaces 59 and 59xe2x80x2 are formed in the vicinity of discharge orifices 54 and ink supplying ports 53. In the spaces, ink stagnates and air bubbles stay there. The air bubbles staying there are hard to remove.
According to the present invention, there is provided an ink jet print head comprising: a fluid passage forming substrate including pressure generating chambers being trapezoidal in shape, which are formed by etching a silicon monocrystalline substrate by anisotropical etching process, each pressure generating chamber having first walls, which are vertical to the surface of the silicon monocrystalline substrate and oriented in the orientation of the pressure generating chambers, and second walls which are slanted at an angle of 35xc2x0 with respect to the surface of the silicon monocrystalline substrate, the second walls being formed at both ends of each pressure generating chamber; an elastic plate firmly fastened onto first opening-formed sides of the pressure generating chambers, pressure generating means for expanding and contracting the pressure generating chambers being mounted on the surface of the elastic plate, and a covering member having nozzle openings each located at the end of each pressure generating chamber and firmly fastened to second opening-formed sides of the pressure generating chambers, the opening of the first opening-formed side being smaller than the opening of the second opening-formed side; wherein the covering member is firmly fastened on the fluid passage forming substrate by adhesive, and meniscuses of the adhesive are formed and hardened in spaces defined by walls slanted at an angle of 35xc2x0 with respect to the surface of the fluid passage forming substrate in which the nozzle openings are formed. The acutely angled spaces are filled with the adhesive walls 15. Each pressure generating chamber has walls substantially parallel to the flowing direction of ink. No stagnation of ink is present in the pressure generating chambers. Accordingly, an object of the present invention is to provide an ink jet print head in which stagnation of ink is removed in the vicinity of nozzle openings and ink supply ports, to thereby eliminate air bubbles staying there, and hence the removability of bubbles is improved.
Another object of the present invention is to provide a method of manufacturing an ink jet print head improved as mentioned above.
Yet another object of the present invention is to provide a method of manufacturing a fluid passage forming substrate for an ink jet print head in which the width of the ink supply ports is not expanded even if the etching patterns are shifted from their correct positions, and the ink supply ports have accurate flow resistance values.